Changing seasonality and phenology mediate the effects of migration across meta-ecosystems

Migration is a ubiquitous process that links ecosystems with distinct seasonal dynamics, transferring biomass and species interactions across space. Despite being widely altered by global change, studies commonly overlook the interaction of seasonal characteristics and bidirectional migration on species coexistence and biomass production across meta-ecosystems. We developed a mathematical model to study how migration interacts with key characteristics of seasonality--amplitude of variation and length of summer--to influence migrant persistence, consumer coexistence, and biomass production. Our findings demonstrate that seasonal characteristics mediate the effect of migration on coexistence and biomass production across meta-ecosystems. However, the effects strongly depend on migration timing: phenological mismatches can reduce biomass at local and meta-ecosystem scales and lead to the extinction of migratory and non-migratory consumers. Our study highlights how migration and seasonality interact to shape community structure and ecosystem function across scales, emphasizing the importance of system-level approaches for studying ecological outcomes of global change.